The present disclosure relates generally to methods for controlling catalyst nanoparticle positioning, and to an apparatus for growing a nanowire.
Since the inception of semiconductor technology, a consistent trend has been toward the development of smaller device dimensions and higher device densities. As a result, nanotechnology has seen explosive growth and generated considerable interest. Nanotechnology is centered on the fabrication and application of nano-scale structures, or structures having dimensions that are often 5 to 100 times smaller than conventional semiconductor structures. Nanowires are included in the category of nano-scale structures.
Nanowires are wire-like structures having at least one linear dimension (e.g., diameter) ranging from about 3 nm to about 200 nm. Nanowires are suitable for use in a variety of applications, including functioning as conventional wires for interconnection applications or as semiconductor devices. Nanowires are also the building blocks of many potential nano-scale devices, such as nano-scale field effect transistors (FETs), p-n diodes, light emitting diodes (LEDs) and nanowire-based sensors, to name a few.
Nanowires may be grown from catalyst nanoparticles. The positioning of such nanoparticles on vertical surfaces is generally not controlled. This lack of control may make it difficult to position the nanoparticles at a desirable distance from a lower region of the vertical surface. In some instances, the lower bound of the nanoparticle position may be controlled; however, such limited control often results in the random positioning of nanoparticles in a top region of the vertical surface. Furthermore, catalyst nanoparticles often form on undesired regions of the substrate where such nanoparticles lead to unwanted nanowire growth, requiring complicated subsequent processing to remove them and obtain the desired structure.